Magnetic resonance imaging of the upper abdomen using a free‐breathing T2‐weighted turbo spin echo sequence with navigator triggered prospective acquisition correction

Abstract

Purpose:To evaluate a free-breathing navigator triggered T2-weighted turbo spin-echo sequence with prospective acquisition correction (T2w-PACE-TSE) for MRI of the upper abdomen in comparison to a conventional T2-weighted TSE (T2w-CTSE), a single-shot TSE (T2w-HASTE), and a T1-weighted gradient-echo sequence (T1w-FLASH). Materials and Methods:A total of 40 consecutive patients were examined at 1.5 T using free-breathing T2w-PACE-TSE, free-breathing T2w-CTSE, and breath-hold T2w-HASTE and T1w-FLASH acquisition. Images were evaluated qualitatively by three radiologists regarding motion artifacts, liver-spleen contrast, depiction of intrahepatic vessels, the pancreas and the adrenal glands, and overall image quality on a four-point scale. Quantitative analysis of the liver-spleen contrast was performed.Results: Depiction and sharpness of intrahepatic vessels were rated significantly better (P Ͻ 0.01) using T2w-PACE-TSE compared to T2w-CTSE and T2w-HASTE sequences. Significantly higher contrast values were measured for T2w-PACE-TSE images compared to T2w-CTSE, T2w-HASTE, and T1w-FLASH images (P Ͻ 0.01). Mean examination time of the T2w-PACE-TSE was 7.91 minutes, acquisition time of the T2w-CTSE sequence was 4.52 minutes. Conclusion:Prospective acquisition correction is an efficient method for reducing respiratory movement artifacts in T2w-TSE imaging of the upper abdomen. Compared to T2w-CTSE and T2w-HASTE sequences recognition of anatomical details and contrast can be significantly improved.

Diffusion‐weighted imaging of the liver: Comparison of navigator triggered and breathhold acquisitions

“…Respiratory triggering is another method that can be proposed to improve image quality of DWI. Respiratory triggering is a technique that attempts to avoid motion artifacts prospectively by using respiratory signals to synchronize the image acquisition with the patient's breathing cycle and by acquiring the imaging data during the relative quite end expiration phase (28,29,38,(55)(56)(57)(58)(59).…”

“…For the monitoring of respiration, various techniques have been used such as registration with bellow systems in combination with a strain gauge, elastic breathing belts, and temperature monitoring using face masks, as well as navigator echoes, a technique primarily used for cardiac imaging (58). The major advantage of navigator echoes is that no additional hardware is needed and easier patient set up.…”

Navigator‐triggered prospective acquisition correction (PACE) technique vs. conventional respiratory‐triggered technique for free‐breathing 3D MRCP: An initial prospective comparative study using healthy volunteers

“…However, there is a possibility that the quality of the images obtained will not be satisfactory because the motion of the abdominal wall does not always synchronize with that of the abdominal parenchymatous organ. As well, patients need to be specially prepared and interruptions of an examination because of the dislocation of the respective monitoring device can occur (5,7).…”

“…The navigator-triggered technique has recently been applied to another motion correction method (5)(6)(7)(8)(9). This technique can reduce respiratory motion artifacts by directly monitoring the movement of the right diaphragm with navigator echoes (5)(6)(7)9).…”

“…This technique can reduce respiratory motion artifacts by directly monitoring the movement of the right diaphragm with navigator echoes (5)(6)(7)9). It has mainly been used for cardiac imaging, called the navigator technique or 1D-prospective acquisition correction (1D-PACE) technique (9 -12).…”